1. Field of the Invention
This invention relates to an improved container for holding food, beverages, and other refrigerated items. These items are preferably maintained in the improved container at temperatures lower than ambient temperatures (e.g., lower than about 60.degree. F. or 70.degree. F.).
2. Description of the Related Art
Food and beverages have long been kept in insulated "coolers" or containers surrounded by ice, thereby maintaining the food and beverages at temperatures lower than ambient temperatures. The ice tends to melt relatively quickly, however, reducing the effectiveness of the cooler, and also potentially subjecting the food and beverages to a contaminating environment.
To address the melted ice problem, containers have been developed which separate the ice from the food or beverages. In addition, media or refrigerants other than ice (e.g., ethylene glycol, propylene glycol, amorphous natural high-polymer carbohydrates) have been used to absorb heat. For instance, U.S. Pat. No. 4,981,234 discloses a two layer container whereby an "amorphous high-polymer carbohydrate comprising long chains of glucose rings" is maintained between the layers. This patent is hereby incorporated by reference.
One disadvantage with two-layer containers such as described in U.S. Pat. No. 4,981,234 is that the refrigerant material may be harmful or distasteful to humans if ingested. As such, if the container holds food or beverages, any leakage of the refrigerant material may contaminant the food. Such leakage is more likely to occur at areas in the container whereby the two layers are joined together.
For instance, in FIG. 3 of U.S. Pat. No. 4,981,234 the two layers are joined together with an inclined inner ridge 21, the underside of which is engaged by an outer projection or ridge 22 on the inner shell 10. In addition, a flange-like extension 23 on the inner shell 10 rests on the upper edge of the outer shell 11. Since the connection area between the two layers in U.S. Pat. No. 4,981,234 is at or near the top of the container, and since leakage tends to occur at the connection area, any leakage that might occur may find its way into the interior of the container, thereby contaminating the food and/or beverages within.
Another potential disadvantage of the system to connect the two layers in U.S. Pat. No. 4,981,234 is that it relies upon mechanical sealing to prevent leakage. When the container is stressed (for instance, during movement), or subjected to thermal expansion (for instance, if left in the sun on a hot day), then the mechanical connection system disclosed in this patent may fail.